Device and method for including passive components in a chip scale package

ABSTRACT

The invention provides a method and device for building one or more passive components into a chip scale package. The method includes the steps of selecting a passive component having a terminal pitch that is a multiple of the package ball pitch of a chip scale package and mounting the selected passive component terminals to ball sites of the package. A preferred embodiment of the invention uses a single metal layer polyamide tape as the substrate of the package. Additional preferred embodiments of the invention are disclosed in which the terminal pitch multiple of the package ball pitch is one or two. Devices corresponding to the disclosed methods are also disclosed.

PRIORITY DATE

This is a divisional application of application Ser. No. 10/103,386filed Mar. 21, 2002, now U.S. Pat. No. 7,105,923 the contents of whichare herein incorporated by reference in its entirety, which claims thebenefit of U.S. Provisional Application No. 60/344,200, filed Dec. 28,2001.

TECHNICAL FIELD

The invention relates to devices and methods for packaging integratedcircuit (IC) devices. More particularly, the invention relates to thepackaging of ICs with accompanying discrete passive components on thesame chip package by forming direct connections between substrate solderballs and IC and discrete component terminals or pads.

BACKGROUND OF THE INVENTION

In use, integrated circuits (ICs) generally require electricalconnections to a substrate to form a package providing electricalconnections to additional electronic devices. In general, in a ball gridarray (BGA), an approximately square package substrate is provided withsolder balls for electrical connection to IC terminals or bonding pads.The package substrate may be composed of multiple layers ofsemiconductor, mask, and conductive materials depending upon thecomplexity of the electrical connections to be made. In practice, themore layers, the higher the manufacturing effort and expense.

IC dice may be packaged alone, but frequently an IC die is included on apackage substrate along with one or more discrete passive componentssuch as resistors, capacitors, and so forth. Including discrete passivecomponents in an IC package typically adds significant development andmanufacturing costs and design complexity to the packaging endeavor.This complexity is engendered by the need for engineering changes to thepackage to accommodate the interconnection of the components selectedfor a particular application. Generally, expenses and complexity arealso increased by the necessity of using multiple layer substrates inorder to make electrical connections among the various discretecomponent terminals, IC terminals, and ball sites of the substrate.

Methods and devices providing the capability of including discretepassive components in an IC chip scale package with reduced cost and areduced need for engineering changes to the package would be desirablein the arts.

SUMMARY OF THE INVENTION

In general, devices and methods providing for the inclusion ofelectrically connected discrete components and ICs in a single chippackage with reduced complexity and expense are disclosed.

According to one aspect of the invention, a method of building one ormore passive components into an existing chip scale package includes thesteps of selecting a passive component having a terminal pitch that is amultiple of the package ball pitch of a chip scale package and mountingthe passive component terminals or pads directly to ball sites of thepackage.

According to another aspect of the invention, a single metal layerpolyamide tape is selected for use as the substrate of the package.

According to still another aspect of the invention, a chip scale packagedevice has at least one IC and at least one discrete passive componentconnected to a package having a preselected ball pitch. The IC terminalsor pads, as well as those of the discrete passive component, are coupleddirectly to ball sites of the package. In order to facilitate directcoupling, the discrete passive component has a terminal pitch that is amultiple of the package ball pitch.

Technical advantages are provided by the invention, including but notlimited to reduced design complexity when engineering a package forselected ICs and discrete passive components. Reduced expense throughthe use of single metal layer substrate and the avoidance of multiplemetal layer substrate. Reduced design and test times due to the readyconnectablitity of components facilitated by the invention. These andmany other advantages related to the improvements of the invention willbecome apparent to persons skilled in the relevant arts through carefulreading of the disclosure and claims presented herein.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention including its features,advantages and specific embodiments, reference is made to the followingdetailed description along with accompanying drawings in which:

FIG. 1 depicts a top view of a package showing an example of theinvention; and

FIG. 2 shows a cross-sectional view of a portion of FIG. 1 taken alongline 2-2 of FIG. 1.

References in the detailed description correspond to like references inthe figures unless otherwise noted. Like numerals refer to like partsthroughout the various figures. The descriptive and directional termsused in the written description such as top, bottom, left, right, etc.,refer to the drawings themselves as laid out on the paper and not tophysical limitations of the invention unless specifically noted. Thedrawings are not to scale and some features of embodiments shown anddiscussed are simplified or exaggerated for illustrating the principlesof the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts whichcan be embodied in a wide variety of specific contexts. It should beunderstood that the invention may be practiced with dice and discretedevices of various types and materials without altering the principlesof the invention.

A preferred embodiment of the invention is shown in the example ofFIG. 1. A package 10 is based on a substrate 12, preferably a singlemetal layer tape substrate although double layer or other multi-layersubstrates may also be used. The substrate 12 contains ball sites 14arranged in a grid pattern and having standardized spacing. For examplespacing, commonly referred to as “ball pitch”, of 0.50 millimeters, or0.80 millimeters is known in the arts. Of course, many alternativepitches are possible. A semiconductor die, typically an IC 16, ismounted on a substrate 12 by connecting die terminals or pads (not shownin FIG. 1) to ball sites 14. Discrete passive components 18, such asresistors, capacitors, etc., are included on the substrate 12 as well.In the preferred embodiments of the invention, the discrete component 18terminals 20 are connected directly to ball sites 14 of the substrate12.

Thus the package 10 is completed without the need for additionalelectrical connections or leads on the substrate 12, avoiding the needin many cases for multilayer substrates. This direct package connectionis achieved by the selection of a ball pitch for the package chosen tomatch the terminal pitch of the discrete component as further describedwith reference to FIG. 2 below.

FIG. 2 is a cross-section view taken along line 2-2 of FIG. 1. Thesingle metal layer tape substrate 12 is shown with a discrete component18 mounted thereon. The ball sites 14 are evenly spaced having apredetermined ball pitch B. The discrete component 18 has apredetermined terminal pitch indicated by T. According to the preferredembodiment of the invention, the substrate 12 ball pitch B is fabricatedto match the terminal pitch T by some whole number multiple. Forexample, as shown in FIG. 2, the terminal pitch T is equal to two timesthe ball pitch B or, T=2×B. Typically, the discrete component 18 isjoined to the substrate 12 by means of a conductive adhesive 28 to thevia cap 24 of the ball site 14 at preselected locations where the soldermask 26 of the substrate 12 has been removed.

In the preferred embodiment of the invention represented in FIG. 2, thediscrete component 18 is a “0402” component having a terminal pitch T of1.0millimeters and the ball pitch B of the substrate 12 has been chosenas 0.50 millimeters. This way, there is a direct correspondence betweencomponent terminals 20 and selected ball sites 14, facilitating thedirect electrical connection of the discrete component 18 to thesubstrate 12 with minimal time and expense, advantageously avoiding thetime and expense otherwise associated with the design and manufacture ofhorizontal and multi-layer connections. Of course, the values shown anddescribed with reference to FIG. 2 are merely examples and are notintended to limit the practice of the invention to any particularnumerical values. To cite but a few additional examples, “0603” discretepassive components may also be used, as may a substrate having a ballpitch of 1.0 millimeter.

The embodiments shown and described above are only exemplary. Eventhough numerous characteristics and advantages of the present inventionhave been set forth in the foregoing description together with detailsof the method and device of the invention, the disclosure isillustrative only and changes may be made within the principles of theinvention to the full extent indicated by the broad general meaning ofthe terms used in the attached claims.

1. A method of building one or more passive components into an existingchip scale package comprising the steps of: providing a substrate havinga plurality of ball sites on one surface thereof, the ball sites havinga preselected pitch; providing an integrated circuit having terminalswhich are coupled directly to ball sites of the substrate; providing apassive component having a pair of fixed pitch position terminalsthereon, said terminals having a terminal pitch that is substantially anintegral multiple of the pitch of the ball sites; and mounting thepassive component terminals directly to ball sites of the package. 2.The method of claim 1 further comprising the step of selecting a passivecomponent wherein the terminal pitch multiple of the package ball pitchis one.
 3. The method of claim 1 further comprising the step ofselecting a passive component wherein the terminal pitch multiple of thepackage ball pitch is two.
 4. The method of claim 1 further comprisingthe step of selecting a package having a ball pitch of 0.50 millimeters.5. The method of claim 1 further comprising the step of selecting apackage having a ball pitch of 1.0 millimeters.
 6. The method of claim 1further comprising the step of using a single conductive layer tape asthe substrate of the package.
 7. The method of claim 1 furthercomprising the step of using a single metal layer polyimide tape as thesubstrate of the package.